From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B513C432BE for ; Sun, 15 Aug 2021 13:03:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4456E60C40 for ; Sun, 15 Aug 2021 13:03:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238228AbhHONEO (ORCPT ); Sun, 15 Aug 2021 09:04:14 -0400 Received: from mout.gmx.net ([212.227.15.15]:44263 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235540AbhHONEL (ORCPT ); Sun, 15 Aug 2021 09:04:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1629032616; bh=nDBvIVcTGEEglcl8qJRL54FMpJmSkZMNNPSxNjHoks0=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=E2DxYj/xc9M7vgSZSZcXstyx/Cf3aB9bveGfA5NaErNU2Ww+XKg9XdyuIiVO4tEU3 5t5sPsEFO17JRbCeVqc7Lu5GKjMYfU/sYnuGElthYPOajOSvnVnBqLwOKSmJ3JHGs+ GuXTcUXCmCdQY7kr4/pmjGaNOVqXdBI95wb4jbfk= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.146.48.238]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MD9X9-1mNoVN15Kz-0095Zd; Sun, 15 Aug 2021 15:03:36 +0200 Message-ID: <7ad059482e56e88bfbe13830cfa06dffee9d071f.camel@gmx.de> Subject: Re: [ANNOUNCE] v5.14-rc5-rt8 From: Mike Galbraith To: Vlastimil Babka , Clark Williams Cc: Sebastian Andrzej Siewior , Thomas Gleixner , LKML , RT Date: Sun, 15 Aug 2021 15:03:35 +0200 In-Reply-To: References: <20210810163731.2qvfuhenolq2gdlv@linutronix.de> <20210812151803.52f84aaf@theseus.lan> <5f0c793d-5084-4607-8475-209fa7310ba2@suse.cz> <20210812162448.26274298@theseus.lan> <20210812164440.0426d8b7@theseus.lan> <96ceab8e-4bf9-147a-e931-848676003c3f@suse.cz> <5dbf6cf9e82ef15ce0febf070608da2d5b128763.camel@gmx.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.40.3 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:aVzwj+nSWqOJH4r4cbOSgXuNepnwo2OErAwZJY+5a48pTOOUu1m QGVbrBHx5Ik2+hgrXbZcsi7muNMh4NwrgDrpBvsB9YYbUfmGD/72JKJAyKJVIaV43eOpR88 9RocKTO1sUGCHERAfobK1iy1q9quwDy7CGRNDLNgSSHe61DJoIN0E+ORaF7o1OnFV5i8dn/ 1zc0Pk2Y3ceCjj14mVmmA== X-UI-Out-Filterresults: notjunk:1;V03:K0:9uHtR7yuSuc=:/9g06wZwyujvjVpilcGuCS Y8ag9TB8gL5eMROe9OwEb67ArtwGv4+Vr2EOFJf5ne34jtVCtIVJsNsVsGrAONbpvW4OHyolM hk8yYfR9lP3zx4ZaD04MvPcvQvkNMg9ylTyRV2+N2wads4X9efcxe3nmhLs8x7xCLm9xzYvVd KDOpE35Dvp5FPt3W6cr15otkzqn1Nt0Ss5zNj4y5GOQPGoiny6VmLEGWt3xZC8GmgyXlA93M2 gWTrtocrT3bSX0tlEWFTtwIexy1KJfh8uaiLJNUgpbTLPJZ2tgjiTIRP7To20w3DOEDW5JDOf or+yU/Zmog4KxPeovATfDuHvtNJqlQ7bWpx9bDID/bpVVFCTg6jpRtAEYEeblNUCwvxhPL+2k i7IOsQm0fOgFABoFqvHBJPwFDDNs+eCFU3Y87XrTc7afLqlbrhwBJsTUFHOR/LL6kDWU5IQj0 niCHVJwgUIYCdtFA3n00PecP+H1j/x8X9aafmu3mPETAKCjLYry67Et79m2Qpt/ucnZouTVdq tnoZARoP02zYP3MP/1nBZaQA6bN/d8E6AP3890RFm1qQ+4alliT7gK0AXhzaR4ANRBXU1hEGX DczOCPt/CNiXvX08+4FZgKS8ugN+hAjV2jrHhySaqAHoCwBSLjTsnWIsgBGHDFBPvuubNlSmg InNRG9YnULpumhMpXC9YQ2UstOo3y4MJpIwDFIspNcJl32zd0vSkifs+aIkXcF/K1FXvSq6vn S+ovcg4Cx39qrLlxjox1Laz67C1WfLYlK6MQOW+RWFfSsyttywrheDLw0RSVhfbZSSZNXJkc5 Z135ZsczMA7BItVRayY4ZfUMYYKkQpn3XC6/vOKcTz1EGmwIkxYAvrndBnOCVIvM82bSFIz/m nt5Rdh4OLId1ArK/CtheDKwZdfEYtgBZqQX9BESD3UMSYIheqAYHtR4Pdq6gWBuLnGs7gls70 URPdEc6cpil7JbZzHJWsmd05wj82+Pg2tJIl1DO8AcYorIuOFz0LzK6nomlm1Mo3TYaXfpoZE Et76f4j863fOOSN/mJhjcxxSgK0PKaHdBSzaVu5p5XPWYubvg1NgF2wSgxblfJAUc/v5QY0K1 uDyyeTPLdnspk12I+3SW5KiCuV+xgyuR/uW Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2021-08-15 at 11:35 +0200, Vlastimil Babka wrote: > On 8/15/21 6:17 AM, Mike Galbraith wrote: > > On Sat, 2021-08-14 at 21:08 +0200, Vlastimil Babka wrote: > > > > > > Aha! That's helpful. Hopefully it's just a small issue where we > > > opportunistically test flags on a page that's protected by the local > > > lock we didn't take yet, and I didn't realize there's the VM_BUG_ON > > > which can trigger if our page went away (which we would have realize= d > > > after taking the lock). > > > > Speaking of optimistic peeking perhaps going badly, why is the below > > not true?=C2=A0 There's protection against ->partial going disappearin= g > > during a preemption... but can't it just as easily appear, so where is > > that protection? > > If it appears, it appears, we don't care, we just leave it there and > won't use it. > > > If the other side of that window is safe, it could use a comment so > > dummies reading this code don't end up asking mm folks why the heck > > they don't just take the darn lock and be done with it instead of tap > > dancing all around thething :) > > Well, with your patch, ->partial might appear just after the unlock, so > does that really change anything? Viewed from pov consumption is optional, it makes sense. -Mike